RESEARCH SUMMARY Adult tissue regeneration shares key genetic requirements with embryonic development. However, despite intense interest from the field of regenerative medicine, the natural mechanisms that allow for the controlled use of embryonic factors to construct functional tissue and organs de novo in adults remains poorly understood. This proposal focuses on the pharynx of the starlet sea anemone Nematostella vectensis as a simple and genetically powerful model system to elucidate the mechanistic similarities and differences between developmental and regenerative organ formation. The Nematostella pharynx is uniquely suited to address this question as it is formed through gastrulation during embryonic development and the functional organ is capable of being regenerated in its entirety following complete removal in the adult. In preliminary experiments, I have identified forkhead box A (foxA), an evolutionarily conserved transcription factor, as expressed in both pharynx development and regeneration. Additionally, through functional genetic analysis I have shown a requirement for foxA in pharynx formation during embryogenesis. This research proposal aims to 1) determine the precise role of foxA in pharyngeal cell determination in a regenerative organism, 2) define the foxA-dependent transcriptional program required for embryonic pharynx formation, and 3) elucidate a regeneration-specific pharyngeal growth program directed by foxA. Functional genetic experiments using transgenic adult animal lines, systemic RNAi, and mosaic gene expression will assess the role of foxA in pharynx development and regeneration. Additionally, RNA sequencing (RNAseq) and chromatin immunoprecipitation DNA sequencing (ChIPseq) analyses will determine embryogenesis-specific and regeneration-specific foxA gene targets and binding sites. These foxA- dependent genes and regulatory binding sites will be further interrogated through genetic perturbation using systemic RNAi and CRISPR-mediated genome editing to mechanistically compare embryonic and post- embryonic organogenesis programs in the same animal. Studies aimed at understanding the similarities and differences of complex organ formation through development and regeneration will reveal deep insight into the natural mechanisms that underlie whole-organ regeneration and could provide conceptual insights to guide the development of future regenerative therapeutics. !